Process of separating shale cuttings from drilling mud containing plastering agents



Nov. 27, 1951 P, CHANEY 2,576,283

PROCESS OF" SEPARATING SHALE CUTTINGS FROM DRILLING MUD CONTAININGPLASTERING AGENTS Filed July 28, 1944 2 SHEETS-SHEET l m/mwrm Nov. 27,1951 P. E. CHANEY 7 2,576,283

I PROCESS OF SEPARATING SHALE CUTTINGS FROM DRILLING MUD CONTAININGPLASTERING AGENTS Filed July 28, 1944 2.SHEETSSHEET 2 ArM/F/VEXS.

Patented Nov. 27, 1951 PROCESS OF SEPARATING SHALE CUTTINGS FROMDRILLING MUD CONTAINING PLAS- TERING AGENTS Preston E. Chaney, Beaumont,Tex, assignor to Sun Oil Company, Philadelphia, Pa., a corporation ofNew Jersey Application July 28, 1944, Serial No. 547,028

11 Claims.

In the normal course of rotary drilling, mud fluid is pumped by means ofa slush pump into the drill pipe (or drill stem). The mud fluid proceedsto the bit at the bottom of the drill pipe and passes through the eyesof the bit at high velocity. The mud fluid then returns to the surfacethrough the annulus between the drill pipe and the wall of the bore holeor the casing, carrying in suspension any shale cuttings which have beendrilled by the rotary motion of the bit. At the surface, the mud isdelivered into a flow line which usually conducts it to a shale shaker.of the vibrating screen type, which serves to separate the mud fluidfrom the shale cuttings. The shale-free mud falls through the vibratingscreen into a suitable mud ditch'or trough, through which it isdelivered to the mud storage tank. The mud fluid is then picked up bythe slush pump for recirculation to complete the cycle.

' While this is the normal procedure in rotary drilling, conditions areencountered which necessitate variation in both the mechanical equipmentand in the properties of the mud fluid. For example, a sand containinggas, oil, or salt water under high pressure may be encountered comesnecessary to increase the density of the mud fluid in order to maintaina hydrostatic pres- 4 Frequently, however, this increase in mud.

weight or density is limited by the loss of mud to uncased porousformations in the bore hole. Thus, for example, it might be found that amud weight of 16 pounds per gallon would be necessary to prevent theflow of fluid from a high pressure zone into the bore hole, but at thesame time a mud weight exceeding 15 pounds per gallon would cause lossof the mud fluid to some lower pressure zone in the well.

In such case, it is necessary to add various mechanical plasteringagents, such as shredded cellophane, flsh scales, mica flakes, or sugarcane flber, to the mud fluid in order to plaster over, or wall oi," thezone to which the mud fluid is being lost. However, at present there isa serious objection to the use of these plastering agents, in that they,together with the shale cuttings, are separated from the mud by theshale shaker. It is then necessary to discontinue the use of the shaleshaker in order to continuously circulate mud fluid containing suchplastering agents.-

However, failure to utilize the shale shaker results in the accumulationof shale cuttings in the mud fluid, which is objectionable inth'at theconcen- 2 tration of shale cuttings may become sufliciently high tocause sticking of the drill pipe, and consequent loss of the bore hole.The object of my invention is to enable certain plastering agents to beadded to the drill mud and to circulate the drilling mud continuouslyand effect the removal therefrom of the shale cuttings without loss ofthe plastering agent from the stream of drilling mud conveyed by theslush pump to the drill pipe. The invention comprises continuouslyseparating the plastering agent and the shale cuttings from the streamof drilling. mud flowing from the bore hole, continuously separating, ashereinafter described, the plastering agent from the shale cuttings, andcontinuously conveying the separated plastering agent to the mud streambeyond the locus therein at which the plastering agent and the shalecuttings were removed therefrom.

In one preferred way of practicing the process, the return mud,containing shale cuttings and any added plastering materials, flowingfrom the well, is conducted over a vibrating screen type of shale shakerin a conventional manner. The shale cuttings and any added plasteringmaterials are screened from the mud and collected at the lower end ofthe shale shaker. The mud falls through the screen and, thus freed fromshale cuttings and plastering agent, is collected in a suitable mudtrough or ditch, through which it flows back to the mud storage pit. Themixture of plastering material and shale cuttings collected at the endof the shale shaker is then subjected to an upwardly directed fluid(liquid or gas), the velocity of which is so regulated as to selectivelylift the plastering material to an elevation at which the mixture ofplastering material and fluid are removable from the zone of separation,while the shale cuttings will not be lifted to such elevation. Theseparated plastering agent is then returned to the mud stream at a locusbeyond the locus of removal therefrom of the plastering agent and shalecuttings; that is, it is conveyed to the trough or ditch through whichthe mud (freed iromshale cuttings and plastering agent) flows back tothe mud storage pit, or it is conveyed direct to the mud storage pit.

The success of that part of the process which separates the plasteringagent from the shale.

cuttings depends upon the possession by the plastering agent of a ratioof surface area to particle weight substantially higher than the ratioof surface area to particle weight characteristic of the shale cuttings.Such relation is characteristic of most plastering agents. Where,however, the particular material used has a ratio of surface area toparticle weight not substantially different from that of shale cuttings,the process herein described for efiecting their separation is notapplicable. This limitation on the operativeness of the process is notaserious one, since effective and eco nomical plastering materialshaving the above,

specified high ratio of surface area to particle H that I have found tobe not only practicable but which practices the process with especialefficiency; it being understood, however, that the I process is notlimited to being carried on in the particular apparatus so illustratedand hereinafter described.

In the drawings: a Fig. 1 is a perspective view of such an apparatusassociated with a known well drilling means and mud fluid circulatingsystem. Fig. 2 is a perspective .view of part of a modified system forFig. 3 is a side view of practicing the process. the means forming partof the apparatus of Fig. 2, for cleaning and drying the separatedmixture of shale cuttings and plastering agent and for sepa-I rating theconstituents of the mixture. Fig. 4 is an end iew or section on the line4-4 of Fig. 3.

From thestorage tank a the drilling mud fluid, carrying in suspension atplastering agent, is pumped through a pipe b into'the drill pipeor drillstem c, through which it proceeds to the bit at the bottom of the drillpipe, there passing through the eyes of the bit and thence returning tothe surface through the annulus between the drill pipe and the walls ofthe bore hole and casing d, carrying in suspension shale" cuttings aswell as the plastering agent. At the surface this mud fluid is deliveredto a flow linee, which conducts it to a shale shaker f. of the knownvibrating screen type, which separates the shale cuttings and plasteringmaterial from the mud fluid.

The mud fluid returns through the trough orditch g to the storage tanka.

The mixture of plastering agent and shale'cuttings collected at thedischarge end of the shale shaker 1 passes through a pipe, tube or othersuitable flow channel h that communicates with a chamber 7' through aside opening therein. Below this side opening is a fluid distributor itconnected with an inlet pipe 2' for admission of water or other fluid.The water pressure or velocity is so regulated as to cause theplastering materials to be carried upward with the water stream to anoverflow pipe m, while permitting the shale cuttings, by reason of theirlower ratio of surface area to particle weight, to fall through the'up-" wardly moving water stream. to below the distributor 10. Here theshale cuttingsare collected by a screw conveyor n and raised to a levelabove the normal water level in the chamber 9' in order that they may becontinuously removed without loss of appreciable amounts of waterthrough the pipe of the screw conveyor.

The plastering agent, together with the water carried out therewith, isdelivered to a traveling endless screen belt 0, through which the waterfalls into a suitable collecting trough (not shown) which prevents itsentry into the mud stream. The substantially dry and clean plasteringmaterial is then conveyed by the traveling screen into the trough orditch y (or direct to the storage tank a), thus being returned to thecirculating system.

It is practicable to utilize, in the chamber 9', a gas, instead of aliquid, for separating the plastering materials from the shale cuttingswithout substantialchange in the apparatus, and it is practicable todesign means quite different from the apparatus shown in Fig. 1 forcarrying out the process, utilizing, as a selective lifting agent,either a liquid or a gas. -In Figs. 2, 3' and 4, a different specificapparatus is illustrated in which a gas is used as the agent forselectively lifting the plastering material and thus separating it fromthe shale cuttings. In this modification the mixture of shale cuttingsand plastering material "delivered. from the shale shaker 1 falls ontoone end of theupper reach of an endless screen belt II which travelsaround end rollers I and [2, one of which is driven by any suitablepower means. Therotary screen belt is shown as inclined to thehorizontal, its lower end adjoining the shale shaker f-and its upperreach moving upwardly and away from the shale shaker. The angle of a; VV veyed beneath a water spray l3, which removes ,over a number of steamjets l5.

rise of the screen'belt Ill to'the horizontal is not criticaland may beof any value between and'60' degrees, but I prefer an angle ofinclination to the horizontal of to degrees. a

Themixture of v shale cuttings and plastering' material, in its travelalong with the belt, is con-'- from the particles of shale cuttings andplaster-- ing material the small quantity of mud fluid and mud solidsremaining on their surfaces.

The mixture, in its further travel, is conveyed beneath a row of steamjets M. The high ve locity steam acts to remove most of the wash waterand thus to dry thesurfaces of the par-' ticles of plastering materialand'shale cuttings. This drying process renders the materials moresusceptible to separation by the procedure that follows, although it maynot be absolutely essential to the satisfactory operation of the device.

The dried mixture, in its continued travel; is then conveyed to a zonebeneathfa hood i6 and The velocity of the steam from jets l5 is soregulated as to lift the particles of plastering materials withinthiszone from the screen belt into the hood l6, while permitting the shalecuttings to remain on the screenbelt and to be conveyed beyond the hoodto the higher end of the screen, whence they fall into a shalepitHlarranged for their reception.

The plastering agents, after entering the hood I6, are delivered into apipe or duct l1, through which they are conveyed to the trough g,wherein they mix with the mud fluid flowing toward the storage tank a.The end of the pipe or ductl'! adjoining the hood may be open and steamfrom a pipe l8 may be injected into, the open end to propel theseparated particles of plaster-, ing materials through the duct l1.

For the steam jets may be, substituted a current of air or any other gaswhich may be given the required velocity by any suitable means.

The process is not dependent for its operationon the use of the specificmechanical instrumentalities shown and described. For example,; anyknown means for separating particles hav-- ing substantially differentratios of surface area to particle weight may be substituted for thespecific separating apparatus herein disclosed. This application is a.continuation in part of s an application filed by 'me'November 6, 19..3, Serial No. 509,186, now abandoned.

. What I claim .and desire. to protect by'Letters Patent is:. 1 1

1. In the process of rotary gdrilling wells involving circulation ofdrilling mud fluid, with removal from the bore hole of shale cuttings,to which mud fluid has ,been added a plastering agent the particlesOfwhich have a ratio of sur face ,areato particle wei htsubstantiallyhigher than the ratio of surface area to particle weight of thecuttings, the improvement which comprises separating from the"drillingimud fluid the mixture of said plastering agent and shalecuttings contained in the stream of such mud fluid plastering agentfrom'the shale cuttings by subjecting the mixture to the action of afluid stream adapted to carry away only the particles having a highratio of surface area to particle weight and conveying the separatedplastering agent to the mud stream at a locus beyond the locus of theremoval therefrom of the plastering agent and shale cuttings, whereby adrilling mud substantially free of shale cuttings, but with the removedplastering agent restored thereto, is conveyed to the drill stem,thereby effecting continuous circulation of the mud fluid withoutaccumulating therein shale cuttings and without substantial loss fromthe stream of any plastering agent not utilized to plaster the borehole.

2. The process defined in claim 1 in which the separation of plasteringagent from the drill cuttings, after their separation from the drillingmud fluid, is effected by feeding the mixture into an enclosed space ofsubstantial height and allowing it to fall therein countercurrent to anupwardly directed fluid stream at a velocity adapted to carry theplastering material to the upper part of the space while allowing theshale cuttings to fall to the lower part of the space and separatelyremoving from said space the shale cuttings and plastering material.

3. The process defined in claim 1 in which a liquid is utilized as theagent for separation of plastering agent from the drill cuttings, and inwhich, after the plastering agent and the drill cuttings are separatedfrom the drilling mud fluid, the separation of the plastering agent fromthe drill cuttings is eifected by feeding the mixture into an enclosedspace of substantial height and allowing it to fall thereincountercurrent to an upwardly directed liquid stream at a velocityadapted to carry the plastering material to the upper part of the spacewhile allowing the shale cuttings to fall to thelower part of the space,separately removing from said space the shale cuttings and the mixtureof plastering material and actuating liquid, and then removing from theplastering material a substantial proportion of the liquid beforeconveying it to the mud stream.

4. The process defined in claim 1 in which a gas is utilized as theagent for separation of plastering agent from the drill cuttings, and inwhich, after the plastering agent and the drill cuttings are separatedfrom the drilling mud fluid, the separation of the plastering agent fromthe drill cuttings is effected by feeding the mixture into an enclosedspace of substantial height and allowing it to fall thereincountercurrent to an upwardly directed gaseous stream at a velocityadapted to carry the plastering material to the upper part of the spacewhile allowing the shale cuttings to fall to the lower part of the spaceand separately iremoving'ifrom" said":

space the sha'lecuttings and i-plastering material. 5. The'processdefined in claim 1 in which theseparation of plastering agent from thedrill cuttings, after their separation'from the drilling mud fluid, iseffected by delivering them to, and distributing them: over, agas-permeable surface and there subjecting them to the action ofupflowing gas having a velocity adapted to-eifecti such separation bylifting substantially all the and shale cuttings, after its separationfrom the drilling mud fluid and before separatingthe constituents of themixture, to the action of an impinging fluid adapted to remove adherentfluid and solid mud.

7. The process defined in claim 1 comprising delivering of the mixtureof shale cuttings and plastering agent, separated from the outflowingmud stream, to, and distributing it over, a moving surface, removing, bymeans of an impinging fluid, from the particles of said mixture in thecourse of its travel adherent fluid and solid mud and subjecting thethus treated moving mixture, in the course of its further travel, toupwardly directed gas under pressure adapted to separate the particlesof plastering agent from the cuttings by selectively liftingsubstantially only the plastering agent within the area of said mixturesubjected to the action of said gas into position to be conveyed to themud stream.

8. The process defined in claim 1 comprising also subjecting the mixtureof plastering agent and shale cuttings, after its separation from thedrilling mud fluid and before separating the constituents of themixture, to the action of a water spray adapted to remove fluid andsolid mud remaining on the surfaces of said constituents and then to theaction of steam jets adapted to dry said surfaces.

9. The process defined in claim 1 comprising delivering the mixture ofshale cuttings and plastering agent, separated from the outflowing mudstream, to, and distributing it over, a moving surface, subjecting thetraveling mixture first to the action of a water spray adapted to removemud fluid and solids remaining on the surfaces of the shale cuttings andplastering agent particles, then to the action of steam jets adapted todry said surfaces, and then to the action of an upwardly directed gasblast adapted to selectively lift the particles of plastering agent fromthe area of the moving surface subjected to said blast.

10. The process defined in claim 1 in which separation of plasteringagent and drill cuttings is effected by delivering the mixture thereofto, and distributing it over, a moving gas-permeable surface and blowinga stream of gas upward plastering agent from the drill cuttings, and inwhich, after the plastering agent and the drill cuttings are separatedfrom the drilling mud 7. fluid, the separation-of the plastering agent.13mm the drill cuttings is effected. by feeding the mix-- ture into. anenclosed space of substantial height and. allowing it to fallthereincountercurrent to anupwardly directed, liquid-stream at avelocity adapted to carry thepl'astering material to the upper part ofthe space while allowing the shale cuttings to fall to the lower part ofthe space, and separately removing :from said space the shale cuttingsand plastering material. A

' PRESTONE'. CHANEY.

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Wuensch Mar. 10, 1942 OTHER REFERENCES Core: Application-of CelluloseFoil, etc., The

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